病人对经治医生不满意时，可以重新选择医生属于（）
A.病人的权利
B.病人的义务
C.医生的权利
D.医生的义务
E.病人和医生共同的义务
参考答案：A
树木地上部与地下部的交界处称为______。
A．根
B．根颈
C．枝干
D．树冠
Xavier, Y vonne, and Zelda each try independently to solve a problem. If their individual probabilities for success are and , respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem ？（）
A.A
B.B
C.C
D.D
E.E
and 
, respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem ？（）